Merriman is a fee-only wealth management firms in the Pacific Northwest having over US$1.5 billion in client assets.
The deal, which went into effect on 31 December 2012, has bought in US$60 billion in client assets to Focus Financial Partners.
Merriman provides wealth management services focusing on investment management and financial planning, including retirement, insurance, estate/wealth transfer, income tax and charitable giving strategies.
The company, which was founded by Paul Merriman in 1983, services over 2,000 clients located across 49 states, with the majority concentrated in the Pacific Northwest region.
Currently, Merriman has 36 employees, nine of whom are financial advisors.
Commenting on the move, Rudy Adolf, founder and CEO of Focus, said: "We are excited to have Merriman join our partnership as it marks our entry into the Seattle market and expands our West Coast presence.
"Focus had a terrific 2012 from a combination of new firms, sub-acquisitions and talented recruits joining our firms, in addition to growth from existing firms. We expect favorable trends to support continued growth in 2013," Adolf added.